Device for sampling molten metal in a ladle or the like



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Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE DEVICE FOR SAMPLINGMOLTEN METAL IN A LADLE OR THE LIKE Howard N. Hubbard and Edward F.Ketterer,

Lorain, Ohio, assignors to National Tube Company, a corporation of NewJersey Application March 23, 1948, Serial No. 16,584

Claims. (Cl. 'i3-425.4)

handled dipper or spoon and pour them into a cast iron chill mold.Samples so taken are satisfactory for chemical analysis but, becausethey are cooled suddenly, do not reveal the grain characteristics orgraphitization to be expected when the metal is cast in a relativelylarge mass and slowly cooled, i. e., when poured in a large mold such asan ingot mold. In the previous practice, a sample of molten iron, forexample, is converted into white chilled cast iron of physicalcharacteristics widely different from those of ordinary gray iron.Micrographic examination of such samples, therefore, gives only limiteduseful information. Taking samples from the surface also involves anever-present danger of contamination of the sample by slag floating onthe metal.

We have invented a novel device for taking samples whereby the foregoingobjections are overcome and a clean, slowly-cooled sample is obl tainedfrom which much significant information may be derived by micrographicanalysis. The sample thus shows accurately the properties the metal inthe main mass will exhibit when cast in molds. In the case of iron, thesample remains normal gray iron instead of being converted to whitechilled cast iron. In a preferred embodiment and practice, we place arefractoryI tube within a shielding sleeve, mount them in one end of atubular or hollow handle and provide the upper end of the tube with aclosure adapted to lthe contents cooled slowly. After freezing, the

sample is removed from the tube.

We are aware that it has been proposed previously to provide a sampledipper with a temporary closure adapted to be destroyed or fused by themolten metal. Our invention utilizes that expedient but is moreparticularly concerned with a sampling device insuring slow cooling ofthe sample whereby the condition of the latter as revealed bymicrographic analysis will have significance in respect to thecharacteristics to be expected of the remainder of the metal when cast.

A complete understanding of the invention may be obtained from thefollowing detailed description and explanation which refer to theaccompanying drawing, the single gure of which is a central verticalsection through our improved sampling device.

Referring in detail to the drawing, an elongated tubular handle I0,which may be a length of pipe of suitable size, has one end bent to forma crook or U-shaped portion Il with a relatively short limb. rIfhe otherend is bent to form a hook Il for suspending the sampling device fromany suitable support. A bell reducer I2 is threaded onto the upturnedlower end of the handle and a sleeve I3 is screwed into the large endthereof. A plate or disc I4 of copper or other metal of high thermalconductivity, having a central orice |48, is seated in the reducer I2for a purpose which will appear later. A reducer I5 is screwed onto theupper end of sleeve I3.

A refractory tube I6 extends through sleeve I3 and bottoms on disc I4which forms a closure. Sealing rings I'I of suitable packing material,such as asbestos wick, are applied to the tube I6 and seal the clearancebetween the tube and the reducers. The tube is preferably inserted inthe sleeve and the sealing rings applied before the sleeve is screwedinto reducer I2. The tube is composed of heat-resisting glass, quartz,graphite or other suitable material capable of withstanding thetemperature of molten iron for a short time at least. It is preferablyabout 5A," inside diameter and about 9" long, and is provided at itsupper end with a temporary closure disc I8 of heat-destructiblematerial, such as pasteboard. The outside diameter of the tube isconsiderably less than the inside diameter of sleeve I3 whereby an airspace I9 is left therebetween.

In using the device described above for sampling, it may rst be coatedon the exterior with a refractory slurry which, after drying, serves toprotect it from the heat of the metal to be sampled. The user'thenseizes the handle I0 and submerges the lower end in the molten metal tobe sampled, e. g., a ladle of iron tapped from a blastfurnace,manipulating the device so that the tube I6 is kept substantiallyvertical. When the handle has been lowered in the metal to a depthsuillcient to cover the upper end of the tube, the closure I8 is burnedout and metal flows into the upper end of the tube. As metal descendsthrough the tube, it displaces any air initially trapped therein whichescapes through orifice or vent I4a in disc I4. The metal which rststrikes the disc is chilled and quickly solidles because 3 of the highthermal conductivity thereof. The disc should be of such mass as tofavor this result. A plug of solid metal is thus formed at the bottom oftube I6 which prevents liquid metal from entering the handle I0 throughorice |12.

When the tube I6 has been filled with molten metal which occurs within afew seconds after destruction of closure I8, the device is removed fromthe bath and may then be hung up by hook Ila until the sample in thetube has solidified after slow cooling. It will be apparent that thesleeve I3 protects the tube I6 in large part, at least, from directcontact with the air, thus preventing rapid cooling or quenching of thesample. The refractory nature of the tube `IIi also delays cooling ofthe sample. When the sample has ccoled substantially to atmospherictemperature, the tube I6 is removed from the sleeve by unscrewing thereducers, and the sample from the tube. Usually the latter requiresdestruction of the tube but the cost thereof is small. A fresh tube witha closure I8 therein and packing I1 at the ends is inserted in thesleeve and the reducers are coupled to the latter preparatory to thenext sampling operation.

The lower end of the sample which is subjected to chilling and quickcooling by Contact with disc I4 is cut off and may be discarded or usedfor chemical analysis. The remainder of the sample, having been slowlycooled, when ground,

etched and polished, reveals the grain structure and degree ofgraphitization to be expected of the main mass of metal if cast in moldsfor slowcooling, as well as giving a rating as to any nonmetallicinclusions, when examined under the microscope in the known manner. Intaking a sample of iron, the sample exhibits the structurecharacteristic of gray iron and is not converted to white chilled castiron.

It will be apparent from the foregoing that and the character of thematerial of whichvthe tube I6 is composed, permits the formation ofgraphitic carbon and leaves the sample in the form of gray iron exceptfor the initially solidified bottom plug in contact with disc I4. yThequanti-ty and distribution of excess carbonmay readily observed. .The`physical examinaa slowly-cooledr representative sample should vmakepossible improved operationpf the blast furnace and the manufacture'of asuperior product.

A sample taken by aid of the invention `fractures easily for visualexamination and is of convenient size for polishing and etchingpreparatory to metallographic analysis. The replaceable tube I6 producesa smooth-surfaced test piece of uniform diameter. Air initiallyentrapped in the tube is completely vented, thus preventing theformation of an unsound specimen. Our irnproved sampling device is welladapted for taking samples from a deep pool, such as a tapping ladle,and it affords a cooling rate which is substantially uniform from sampleto sample, regardless of variations in atmospheric conditions.

Although we have illustrated and described but a preferred embodimentand practice of the invention, it will be recognized that changes in thedetails and arrangement disclosed may be made without departing from thespirit of the invention or the scope of the appended claims.

1. A device for taking samples of molten metal comprising a refractorytube, a shielding sleeve surrounding said tube, a handle to which oneend of said tube and sleeve are secured, said handle having an exitpassage for air displaced from said tube, and a disc at said one end ofsaid tube having an air vent therein.

2. In a device for sampling molten metal, an elongated member adapted tohave one end immersed in the metal, a refractory tube extending upwardlyfrom said one end of said member, said member having a passage for airdisplaced from said tube, and a closure at the lower end of the tubehaving an air vent therein.

3. The apparatus dened by claim 2 characterized by a shielding sleevesurrounding said tube.

4. In a device for sampling molten metal, an elongated handle, asampling tube xed at one end of said handle and extending upwardlytherefrom, said handle having an exit passage for air displaced fromsaid tube, and a disc at the lower end of said tube having an air venttherein.

5. The apparatus defined by claim 4 characterized by a shielding sleevesurrounding said tube.

6. The apparatus defined by claim 4 characterized by said handle beingtubular.

7. In a device for sampling molten metal, a. U-tube, one limb of whichis shorter than the other, a sampling tube fixed in and extendingupwardly from said shorter limb, and an orifice plate at the bottom ofsaid sampling tube permitting the escape of air but restricting flow ofmetal from the sampling tube to the U-tube.

8. The apparatus defined by claim 7 characterized by a shielding sleevesurrounding said sampling tube.

9. A device for sampling molten metal comprisnga tubular handle, ashielding sleeve secured to one end of said handle and extendingupwardly therefrom a sampling tube disposed within said sleeve, and anorifice plate at the bottom of the sampling tube.

10. The apparatus defined by claim 9 characterized by said handle havinga crooky at said one end.

HOWARD N. HUBBARD. v EDWARD F. KETTERER.

v'milnmnvclis CITED The following references are of record in the le ofthis patent:

OTHER REFERENCES American Institute of Mining and MetallurgicalEngineers, vol. 122, 1936, p. 197.

